Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

128
FXUS63 KLOT 041130
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
530 AM CST Wed Feb 4 2026

.KEY MESSAGES...

- Stagnant temperatures today will warm above freezing by
  Friday, ending a prolonged stretch of daily highs below 32
  degrees at both Chicago and Rockford.

- A pair of clipper systems will race through the area Thursday
  and Thursday night, bringing primarily snow showers. Little to
  no wintry accumulation is currently expected with either
  system.

- A pattern change toward warmer temperatures (highs and lows
  both above freezing) may materialize by the middle of next
  week.

&&

.DISCUSSION...
Issued at 247 AM CST Wed Feb 4 2026

Through Tonight:

Baggy and somewhat disorganized aggregate upper-level cyclonic
flow is in place across the Mississippi River Valley and Great
Lakes this morning, atop a broad surface high pressure system
centered generally near the MN/IA/WI/IL border regions. Weak
convergence down the lake (a consequence of heavy clouds in
Lower Michigan preventing a more formidable land breeze from
developing) and meager lake-induced inversion heights (near
3500ft, per recent AMDAR soundings) have thus far kept lake
effect snow activity to a minimum. At this point, feel the cat
is out of the bag for anything meaningful to develop. So, will
downgrade PoPs along the lakeshore to the "isolated" category
and remove snow accumulations this morning.

Unlike lake effect snow, lake-induced stratus is quite
prevalent across the area this morning, and is in fact
increasing in coverage at press time. Easterly steering flow
will stagnate by mid-afternoon, and then transition to westerly
during the afternoon. Accordingly, much of the area will
probably be stuck beneath clouds all day. For this reason,
temperatures may not move much during daylight hours, with most
areas stalling in the mid 20s.

Inversion heights should lower this evening as the back edge of
the aggregate troughing slides overhead. As a result, would
expect holes in clouds to develop and spread, allowing for skies
to clear (this is not a guarantee, though). Assuming clouds do
start to scatter out, the arrival of the center of the surface
high to calm winds will support efficient radiational cooling.
So, will go ahead and maintain lows tonight generally in the
teens. Where clouds remain, lows could very well verify in the
20s.


Through this Weekend:

Thursday night into Friday, a pair of clipper systems will dive
through the Great Lakes presenting 4 to 6 hour windows for snow
showers. The first clipper will race through the area in the
late morning through early afternoon hours on Thursday, with
the second during the overnight/early Friday morning hours. Low-
level moisture looks marginal with both clippers, especially
with westward extent, so will draw a gradient in PoPs ranging
from 10 to 20% near I-39 to 30 to 40% near Lake Michigan with
both clippers. Precipitation type should be decidedly snow with
the first clipper, but may end up a wintry mix with the second.
Overall precipitation amounts look meager (<0.05") with both,
so would not anticipate any impacts to roads including if a
wintry mix does materialize with the latter. Will be watching
for any trends upward or westward in the strength/track of the
clippers though in future forecasts.

Aggressive warm-air advection ahead of the clippers should
allow for temperatures to rise above freezing for much of the
area on Thursday. Even on Friday, temperatures look to warm
further as the push of cold air associated with the overarching
upper-level troughing supporting the clippers lags behind. As a
result, the stretch of days with high temperatures below
freezing at both Rockford and Chicago should soon come to an
end. (The final tally will be either 20 or 21 days at either
site...hardly a record, but certainly not something that happens
every year).

A glancing blow of another pool of seasonably cold air will
render temperatures to fall this weekend. Mean GEFS/EPS highs
settle into the 20s on Saturday and warm toward 30 on Sunday.
Will note the NBM, which informs our extended forecast, is
currently 4 to 6 degrees warmer than input ensemble suites. So,
would expect our forecast highs to lower as we get closer and
can more readily adjust the temperatures.


Next Week:

Ensemble model guidance remains in agreement that the upper-
level flow will shift from a persistent northwesterly flow
pattern to more of a southwesterly flow pattern through the
course of next week. Am starting to see a fly in the ointment in
a more pristine pattern shift, being a cut-off wave meandering
along the US/Mexico border during the first half of the week.
With that said, the signal remains in ensemble mean fields for
temperatures to increase next week with highs generally in the
40s and lows generally near the freezing mark. There is still a
signal for a synoptic system somewhere in the broad central US
region in the February 11 to 14 timeframe, which would probably
present the next opportunity for inclement weather.

Borchardt

&&

.AVIATION /12Z TAFS THROUGH 18Z THURSDAY/...
Issued at 529 AM CST Wed Feb 4 2026

MVFR stratus streaming off Lake Michigan will persist through
most of the day at the Chicago terminals, though ORD and
especially DPA may scatter by mid-afternoon. Much of the cloud
layer is shallow (under 2kft thick) and contains at least some
super-cooled droplets per recent light icing reports during
approach to ORD. Any agitation of the cloud layer will allow for
glaciation and downstream SHSN through much of the the morning
at MDW and near ORD/GYY. Precip chances should end by early
afternoon as the cloud layer thins.

N/NNW winds 5-10 knots at TAF issuance will gradually back WNW
through the day, and SW overnight. A quick-moving mid-level wave
will track southeast across Lake Michigan on Thursday and
produce a shield of SN northeast of the Chicago terminals. This
SN could brush the terminals if top-down saturation is
sufficient. Have included PROB30 SN with low-end MVFR visibility
late in the morning, though any thorough saturation will likely
yield IFR visibility.

Kluber

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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